The present invention concerns a hot channel injection molding die including an injection die with a nozzle body having an injection channel, a heating jacket enclosed by a casing and surrounding the nozzle body, and an electrical element. The invention also concerns a hot channel injection molding die including a hot runner plate with a heater, wherein at least one distribution conduit in the hot runner plate conducts plastic material from a discharge sleeve to at least one injection nozzle.
With the conventional hot channel injection molds, also called hot runner molds, liquid plastic fed by the feeding screw conveyors of the injection machine is conducted into a heated distribution block to the injection nozzles arranged at a distance from a side face of the same. The distribution conduits within the distribution block are usually created by bore holes lying at right angles to one another. The production of such a distribution block with distribution channels running at right angles to one another is very expensive, and despite expensive processing methods, sharp edges arise on the right angle intersections of the channels which, for one, can damage plastic material transported in them, and on which deposits can establish themselves. Furthermore, the heating of the known distribution blocks has only been unsatisfactorily worked out, since higher temperatures occur in channels situated respectively closer to the heating rods than in regions further removed. Moreover, the temperature profile in the individual channels is different. This can lead to local uncontrolled overheating of the plastic material, especially when the machine is shut down for a time during production interruptions.
The same problems with reference to temperature profiles also occur in hot channel dies in injection molds. For their heating, electrical resistance wires are arranged around or in the nozzle (die) body. The resistance wires can be embedded in a carrier material substrate or be arranged directly on the surface of the nozzle body. The nozzle body is joined at the foot end in the injection mold with the heat channel distributor in a heat-conducting manner, and the hot channel plate is likewise joined at the outflow side with the base plate forming the cavity. Heat flows over these contact points from the hot channel distributor block into the nozzle body, and from the nozzle body into the hot channel plate, and on the base plate side heat flows from the heated nozzle to the cooled base plate. These inflows and outflows of heat have the effect that the nozzle is not evenly heated over its entire length. The temperature profile is, however, also not uniform in its radial extension. This non-homogeneous heat distribution can lead to the consequence that individual sections of the nozzle can damage the plastic material to be injected due to overheating, which leads to sacrifices in quality of the product generated by the plastic injection machine.